Updates to latest version of QEMU.
The build system has changed to ninja.
There are several configuration flags that aren't enabled. I will
defer to maintainers on those.
Adds autoPatchelfHook for patching output dynamically linked binaries.
qemu: use Nix's meson vs bundled
qemu: remove custom directory locations
It appears that these directories are no longer automatically prefixed
with $out/, so they are now trying to write to the system /etc/, /var/
directories, which is not permitted in sandbox.
The default directories seem to work OK, so using those.